tonight, president trump taking swift action to roll back much of president Obama's climate change policies. The president signing a sweeping order today. The coal miners standing next to him. He would bring back coal mining jobs. The white house was pressed today. How many jobs will this move create and will coal jobs really come back in big numbers for those families who heard the promise. Cecilia Vega at the white house. Our incredible coal miners. Reporter: Surrounded by coal miners, the president, with the stroke of a pen, signing a sweeping order to roll back most of president Obama's climate change legacy. With today's executive action, I am taking historic steps to lift the restrictions on American energy, to reverse government intrusion, and to cancel job-killing regulations. Reporter: The order calls for a review of rules curbing carbon emissions in the U.S. It strikes rules mandating that climate change be considered in federal policymaking. It does not address the 2015 Paris climate deal, an international agreement to cap greenhouse gas emissions. The president also promising to We are going to put our coal miners back to work! Reporter: Today, president trump said miners he's met want to get back to work. I said, "How about this? Why don't we get together, we'll go to another place, and you'll get another job. You won't mine anymore. Do you like that idea?" They said, "No, we don't like that idea. We love to mine. That's what we want to do." I said, "If that's what you want to do, that's what you're going to do." Reporter: But the white house doesn't know exactly how many new mining jobs will come out of this executive order. Environmentalists say the president is overselling the revival of jobs in a declining industry. Fewer than 75,000 coal mining jobs remain in the U.S. By comparison, there are more than 650,000 renewable energy jobs. Today the Sierra club called the president's action, "The single biggest attack on climate action in U.S. History, period." Candidate trump called climate change a hoax. It's a hoax. It's a moneymaking industry, okay? It's a hoax, a lot of it. Reporter: Today, we asked the white house if anything has changed. Does the president still believe that climate change is a hoax? He does not believe that as I mentioned at the onset, that there is a binary choice between job creation, economic growth and caring about the environment, and that's what we should be focusing on. Cecilia Vega with us live from the white house tonight. So many coal mining families heard those promises in the campaign from then-candidate Donald Trump. How many jobs this new executive order would create. He didn't have answer. The white house doesn't have an estimate. Sean spicer turning the focus from workers to coal companies. The industry is applauding this order.

This transcript has been automatically generated and may not be 100% accurate.

Scott Pruitt, the head of the Environmental Protection Agency, expressed doubt whether carbon dioxide from human activity is the primary cause of climate change, apparently contradicting the language used on his own agency's website.

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